循环水养殖系统(RAS)生物载体上微生物群落结构变化分析

Analysis of the Changes of Microbial Community Structure on Bio-carrier of Recirculating Aquaculture Systems(RAS)

为研究循环水养殖系统(recirculating aquaculture systems,RAS)生物滤池挂膜及运行过程中生物载体上微生物群落结构的变化及其脱氮机制,采用传统微生物培养方法,对不同时期生物载体上的异养细菌、氨氧化细菌及硝化菌进行培养计数.并通过变性梯度凝胶电泳技术,对细菌的16S rDNA V3可变区的PCR扩增片段进行分离,分析了所得到的细菌群落特征DNA指纹图谱,对其中的优势菌属使用序列数据进行同源性分析并建立系统发育树.结果表明,随着时间的推移,3类细菌的数量都呈现出先增加后逐渐降低直至达到稳定的趋势.各个时期生物载体上微生物群落的组成非常丰富,Shannon指数分别为1.53、1.44、1.57、1.08、1.27和1.30.不同时期生物载体上微生物的种类有一定的变化,但2个相邻时期的Cs值(相似性指数)都比较高,说明微生物群落的变化与演替是缓慢而有规律的.生物载体上存在多类细菌共同作用于养殖水体污染物的去除,出水水质能达到高密度养殖的要求,其主要优势种群以Proteobacteria和Flavobacteria为主,分离鉴定出了亚硝化单胞菌属(Nitrosomonas)及黄杆菌(Flavobacteriaceae bacterium)等兼性厌氧细菌,表明生物滤池中可能同时存在硝化和脱氮途径.

In order to study the variation of microbial community structure and the mechanism of denitrification on bio-carrier in recireulating aquaculture systems（RAS） during the periods of bio-film formation and operation the systems, traditional microbiological methods were applied to count the quantity of heterotrophic bacteria, ammonia oxidize bacteria and nitrite oxidize bacteria. The amplified products of variable V3 region of bacterial 16S rDNA were separated by using denaturing gradient gel electrophoresis （DGGE）. And bacterial community DNA fingerprint was obtained. The sequences retrieved from the DGGE bands were used for homology analysis and construction of phylogenetic tree. It presented a trend that the quantity of the three types of bacteria increased gradually to a top and then fallen slowly to a stable level. The composition of microbial community of bio-carrier was very abundant in all periods, and the Shannon index was 1. 53, 1.44, 1.57, 1.08, 1.27 and 1.30, respectively. During different periods, there was a certain shift in the microbial community structure, while the C, value（similar index） in two adjacent periods was high, indicating the variation and succession of the microbial community was slow and regular. Several bacteria had an effect on removal of pollutants for farming water and the effluent water quality could meet the requirements of high-density culture. Among them, Proteobacteria and Flavobacteria were main communities. The Nitrosomonas and some other faeuhative anaerobic bacteria（ Flavobacteriaeeae bacterium） were identified, which indicated that there may be coexisted pathways of nitrification and denitrification in bio-fiher.